Just found out my boyfriend is still smoking even though he said he quit.

Alexandria
So my bf had to move back in with his dad to help him out for a little bit and his dad smokes so I didn't think much of find packa there at first. Until I started to notice them more around where my boyfriend would spend his time. I asked him about it and he said his friend would come over and smoke while they hung out. Then today I found out from his brother that he's been smoking again and I just don't know what to do. He had quit before we started dating and I'd told him beforehand that I'd never date a smoker.... :/